亚胺培南耐药鲍曼不动杆菌小鼠肺部感染模型建立

Establishment of mice pneumonia model with imipenem-resistant Acinetobacter baumannii

目的 建立亚胺培南耐药鲍曼不动杆菌小鼠肺部模型,为泛耐药鲍曼不动杆菌抗感染研究提供实验动物模型.方法 随机选取120只约4周大雄性BALB/C小鼠,平均分成3组：微量气管注射法组、超声雾化法组和滴鼻法组.每组小鼠用甲氨蝶呤化疗降低BALB/C小鼠的免疫力,然后将亚胺培南耐药鲍曼不动杆菌分别用微量气管注射法、超声雾化法、滴鼻法感染免疫力低下和正常的BALB/C小鼠,检测微量气管注射法、超声雾化法、滴鼻法感染的小鼠感染率、死亡率、细菌清除率、肺部病理变化.结果 微量气管注射法、超声雾化法感染免疫力低下的BALB/C小鼠的肺部感染率均为100%（30/30）,死亡率分别为100%（10/10）,33%（3/10）,2组小鼠肺部细菌感染12～24 h后支气管周及肺泡间质内见中性粒细胞、淋巴细胞、巨噬细胞为主的炎症细胞浸润,微量气管注射法感染的小鼠部分肺泡组织结构崩解,肺泡腔内可见脓肿形成及较多细菌集落,超声雾化法感染的小鼠24 h见肺部部分区域存在细胞变性,但支气管及肺泡组织结构基本正常,肺泡壁血管轻度扩张伴淤血,24～48 h后可见支气管和支气管周围变性,部分肺组织血管高度扩张,伴有水肿,48 h后炎症逐渐恢复.滴鼻法感染免疫力低下的BALB/C小鼠的肺部感染不明显,未见小鼠死亡（0/10）,肺部无明显病理变化.结论 免疫力低下BALB/C小鼠可以通过微量气管注射法和超声雾化法建立亚胺培南耐药鲍曼不动杆菌肺部感染模型,超声雾化法可以大批量同时操作,简单经济快速,实用性强.亚胺培南耐药鲍曼不动杆菌难以感染免疫力正常小鼠.

Objective To construct the mice pneumonia model with imipenem-resistant Acinetobacter baumannii and provide experimental model in anti-pan-resistant Acinetobacter baumannii therapy study. Methods A total number of 120 4-week-old BALB/C male mice were randomly selected and divided into three groups including micro-intratracheal injection, ultrasonic atomizing and nasal dripping. The mice were treated with methotrexate to induce hypo-immunity in every group. These BALB/C mice of normal immunity and hypo-immunity were infected through Imipenem-resistant Acinetobacter baumannii by microintratracheal injection, ultrasonic atomizing and nasal dripping, respectively. The morbidity, mortality,bacterial clearance rate and histopathology in lung were determined. Results The morbidities of BALB/C mice with hypo-immunity infected by micro-intratracheal injection and ultrasonic atomizing achieved 100%（30/30）, while the mortalities were 100% （10/10） and 33.3% （3/10）, respectively. Mice in two groups above displayed the influx of neutrophils, lymphocytes and macrophages in the peri-bronchial and alveolar interstitial space 12-24 h after pulmonary infection. In addtion, the mice in micro-intratracheal injection group displayed coUapse of partial alveolar walls, formation of abscesses and bacterial colonies in alveoli. While the lung pathology in mice of ultrasonic atomizing group was characterized by cell degeneration in some regions in the lungs, slight relaxation, congestion in alveolar wall vessels and normal of bronchial and alveolar tissue 24 h after inoculation. Degeneration in peri-tracheal and peri-bronchial areas was observed 24-48 h after inoculation, along with highly expanded pulmonary blood vessels and edems. The inflammation was reduced at 48 hours. There was no obvious pulmonary infection in BALB/C mice with hypo-immunity by nasal dripping with mortality of 0% （0/10） and no significant histopathologic change in lungs. Conclusions BALB/C mice with hypo-immunity pneumonia model with Imipenem-resistant Acinetobacter baumannii can be conducted by micro-intratracheal injection or ultrasonic atomizing, but the latter has the advantages of high-productivity, easy-operation, low-cost, time-saving and usefulness. Mice with normal immunity are not susceptible to imipenem-resistant Acinetobacter baumannii.